Microwave generating device and method

Abstract

The present invention provides a microwave generating device and method, the device includes: a frequency doubling module, the frequency doubling module includes an intensity modulator, a laser and a first optical coupler; wherein the intensity modulator is used to superimpose a frequency-sweeping optical signal and a frequency-sweeping microwave signal in an optoelectronic oscillation loop to generate a frequency-doubled optical signal, and the maximum frequency of the frequency-doubled optical signal is the sum of the maximum frequency of the frequency-sweeping optical signal and the maximum frequency of the frequency-sweeping microwave signal; the laser is used to generate a laser signal; the first optical coupler is used to couple the frequency-doubled optical signal and the laser signal to generate a broadband frequency-doubled optical signal. The microwave generating device of the present invention realizes the generation of a frequency-doubled microwave signal with rapid frequency sweeping.

Description

Technical Field

[0001] The present invention relates to the technical field of microwave photonics, and in particular to a microwave generating device and method. Background Art

[0002] The generation of microwave signals is a long-term research direction in the field of microwave photonics technology. The traditional method of generating microwave signals electrically has many disadvantages, such as poor signal quality, difficulty in generating high frequencies, and difficulty in broadband tuning.

[0003] With the development of microwave photonic technology, people use optoelectronic modulation and demodulation to build optoelectronic oscillators to generate microwave signals, which can effectively solve the drawbacks of traditional electrical methods of generating microwave signals. However, the existing method of using optoelectronic oscillators to generate microwave signals cannot achieve frequency doubling and rapid continuous frequency scanning at the same time. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] In view of the existing technical problems, the present invention provides a microwave generating device and method for at least partially solving the above technical problems.

[0006] (II) Technical solution

[0007] The present invention provides a microwave generating device, comprising: a frequency doubling module A, the frequency doubling module A comprising an intensity modulator 1, a laser 2 and a first optical coupler 3; wherein the intensity modulator 1 is used to superimpose a frequency-sweeping optical signal and a frequency-sweeping microwave signal in an optoelectronic oscillation loop B to generate a frequency-doubled optical signal, and the maximum frequency of the frequency-doubled optical signal is the sum of the maximum frequency of the frequency-sweeping optical signal and the maximum frequency of the frequency-sweeping microwave signal; the laser 2 is used to generate a laser signal; and the first optical coupler 3 is used to couple the frequency-doubled optical signal and the laser signal to generate a broadband frequency-doubled optical signal.

[0008] Optionally, the optoelectronic oscillation loop B includes: a swept-frequency light source 4, a second optical coupler 5, and a phase modulator 6, a long optical fiber 7, a notch filter 8, a first photodetector 9, an amplifier 10 and an electrical coupler 11 connected in a ring in sequence; wherein the swept-frequency light source 4 is used to generate a swept-frequency optical signal; the second optical coupler 5 is used to output one swept-frequency optical signal to the phase modulator 6, and output another swept-frequency optical signal to the intensity modulator 1; the phase modulator 6 is used to modulate the swept-frequency optical signal and a swept-frequency microwave signal output by the electrical coupler 11 to generate equal-magnitude anti-phase optical sidebands; the long optical fiber 7 is used to increase the delay of the swept-frequency optical signal and the equal-magnitude anti-phase optical sidebands in the optoelectronic oscillation loop B; the notch filter 8 is used to filter the equal-magnitude anti-phase optical sidebands to obtain a single optical sideband; the first photodetector 9 is used to convert the single optical sideband into a swept-frequency microwave signal; the amplifier 10 is used to amplify the swept-frequency signal; and the electrical coupler 11 is used to output one of the swept-frequency microwave signals to the intensity modulator 1.

[0009] Optionally, the effective length of the optical fiber connecting the second optical coupler 5 and the intensity modulator 1 is equal to the effective length of the cable connecting the electrical coupler 11 and the intensity modulator 1, and the effective length is the same transmission time, the length of the optical fiber transmitted by the optical signal in the optical fiber or the length of the cable transmitted by the electrical signal in the cable.

[0010] Optionally, the optoelectronic oscillation loop B includes at least one loop.

[0011] Optionally, the optoelectronic oscillation loop B includes a long optical fiber 7 or at least two long optical fibers 7 connected in parallel, and the at least two long optical fibers 7 are of different lengths.

[0012] Optionally, the optoelectronic oscillation loop B includes at least one amplifier 10 , and the amplifier 10 includes a first optical amplifier 101 and / or an electrical amplifier 102 .

[0013] Optionally, the notch filter 8 includes any one of a phase-shifted fiber Bragg grating, a Fabry-Perot resonant cavity, a gas absorption cell or a microring.

[0014] Optionally, the optical path of the optoelectronic oscillation loop B includes at least one polarization controller 12, and the polarization controller 12 is used to adjust the polarization direction of the optical signal.

[0015] Optionally, the frequency doubling module A also includes: a second optical amplifier 13, an optical filter 14, and a second photodetector 15; wherein the second optical amplifier 13 is used to amplify the frequency doubling optical signal; the optical filter 14 is used to filter out the non-frequency doubling optical signal output by the intensity modulator 1; and the second photodetector 15 is used to convert the broadband frequency doubling optical signal into a broadband frequency doubling electrical signal.

[0016] On the other hand, the present invention provides a microwave generation method, comprising: generating a frequency-doubled optical signal by superimposing a frequency-swept optical signal and a frequency-swept microwave signal in a photoelectric oscillation loop B through an intensity modulator 1, wherein the maximum frequency of the frequency-doubled optical signal is the sum of the maximum frequency of the frequency-swept optical signal and the maximum frequency of the frequency-swept microwave signal; generating a laser signal through a laser 2; and coupling the frequency-doubled optical signal and the laser signal through a first optical coupler 3 to generate a broadband frequency-doubled optical signal.

[0017] (III) Beneficial effects

[0018] The present invention provides a microwave generating device, which modulates a swept frequency optical signal and a swept frequency microwave signal of the same source in a photoelectric oscillation loop through an intensity modulator to generate a doubled frequency optical signal, which is then coupled with a laser signal generated by a laser and finally photoelectrically converted to achieve frequency doubling of the microwave signal.

[0019] The swept frequency light source, phase modulator, long optical fiber, notch filter, first photodetector, amplifier and electric coupler constitute a Fourier domain mode-locked optoelectronic oscillation loop, which can generate fast swept frequency microwave signals. Combined with the frequency doubling module, the generation of fast swept frequency doubled microwave signals is realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0021] Figure 1 A diagram schematically shows a microwave generating device according to an embodiment of the present invention;

[0022] Figure 2 A modulation principle diagram of an intensity modulator according to an embodiment of the present invention is schematically shown;

[0023] Figure 3 A schematic diagram showing the working principle of a notch filter according to an embodiment of the present invention is shown;

[0024] Figure 4 A diagram schematically shows a microwave generating device according to another embodiment of the present invention;

[0025] Figure 5 A diagram schematically shows a microwave generating device according to another embodiment of the present invention;

[0026] Figure 6 A flow chart of a microwave generating method according to an embodiment of the present invention is schematically shown.

[0027] [Description of Reference Numerals]

[0028] 1-Intensity Modulator

[0029] 2-Laser

[0030] 3-First optical coupler

[0031] 4-Swept frequency light source

[0032] 5- Second optical coupler

[0033] 6-Phase Modulator

[0034] 7-Long Fiber

[0035] 8-Notch filter

[0036] 9-First photodetector

[0037] 10-Amplifier

[0038] 101-First Optical Amplifier

[0039] 102-Electric Amplifier

[0040] 11-Electric coupler

[0041] 12-Polarization Controller

[0042] 13- Second optical amplifier

[0043] 14-Optical filter

[0044] 15- Second photodetector

[0045] A-frequency multiplier module

[0046] B-Photoelectric Oscillation Loop DETAILED DESCRIPTION

[0047] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0048] It should be noted that in the drawings or descriptions, similar or identical parts use the same figure numbers. The technical features in the various embodiments exemplified in the specification can be freely combined to form a new solution without conflict. In addition, each claim can be used as an embodiment alone or the technical features in each claim can be combined as a new embodiment. In the drawings, the shape or thickness of the embodiment can be expanded and simplified or conveniently indicated. Furthermore, the elements or implementations not shown or described in the drawings are in a form known to a person of ordinary skill in the art. In addition, although demonstrations of parameters containing specific values ​​may be provided herein, it should be understood that the parameters do not need to be exactly equal to the corresponding values, but can be approximated to the corresponding values ​​within an acceptable error tolerance or design constraint.

[0049] Unless there are technical obstacles or contradictions, the above-mentioned various embodiments of the present invention can be freely combined to form other embodiments, and these other embodiments are all within the protection scope of the present invention.

[0050] Although the present invention is described in conjunction with the accompanying drawings, the embodiments disclosed in the drawings are intended to exemplify the preferred embodiments of the present invention and should not be construed as limiting the present invention. The size ratios in the drawings are merely illustrative and should not be construed as limiting the present invention.

[0051] Although some embodiments of the present general inventive concept have been shown and described, it will be appreciated by those skilled in the art that changes may be made to these embodiments without departing from the principles and spirit of the present general inventive concept, the scope of which is defined by the claims and their equivalents.

[0052] Figure 1 A diagram schematically shows a microwave generating device according to an embodiment of the present invention.

[0053] According to an embodiment of the present invention, Figure 1 As shown, the microwave generating device includes, for example, a frequency doubling module A, which includes, for example, an intensity modulator 1, a laser 2, and a first optical coupler 3. The intensity modulator 1 is used to superimpose the swept frequency optical signal and the swept frequency microwave signal in the photoelectric oscillation loop B to generate a frequency doubling optical signal, and the maximum frequency of the frequency doubling optical signal is the sum of the maximum frequency of the swept frequency optical signal and the maximum frequency of the swept frequency microwave signal. The laser 2 is used to generate a laser signal. The first optical coupler 3 is used to couple the frequency doubling optical signal and the laser signal to generate a broadband frequency doubling optical signal.

[0054] According to an embodiment of the present invention, the optoelectronic oscillation loop B includes, for example: a swept-frequency light source 4, a second optical coupler 5, and a phase modulator 6, a long optical fiber 7, a notch filter 8, a first photodetector 9, an amplifier 10 and an electrical coupler 11 connected in a ring in sequence. The swept-frequency light source 4 is used to generate a swept-frequency optical signal. The second optical coupler 5 is used to output a swept-frequency optical signal to the phase modulator 6, and output another swept-frequency optical signal to the intensity modulator 1. The phase modulator 6 is used to modulate the swept-frequency optical signal and a swept-frequency microwave signal output by the electrical coupler 11 to generate optical sidebands of equal magnitude and inverse phase. The long optical fiber 7 is used to increase the delay of the swept-frequency optical signal and the optical sidebands of equal magnitude and inverse phase in the optoelectronic oscillation loop B. The notch filter 8 is used to filter the optical sidebands of equal magnitude and inverse phase to obtain a single optical sideband. The first photodetector 9 is used to convert the single optical sideband into a swept-frequency microwave signal; and the amplifier 10 is used to amplify the swept-frequency signal. The electrical coupler 11 is used to output one of the swept-frequency microwave signals to the intensity modulator 1.

[0055] According to an embodiment of the present invention, since the unconverted swept frequency optical signal in the photoelectric oscillation loop B and the swept frequency microwave signal converted from the swept frequency optical signal have the same source, for example, they can be the swept frequency light source 4, and thus the fast-tuned microwave photon filter, that is, the photoelectric oscillation loop B, can be used to achieve fast and continuous frequency sweeping of the microwave signal. The swept frequency optical signal and the swept frequency microwave signal are modulated and superimposed by the intensity modulator 1. The superimposed optical signal has a high frequency, for example, at the terahertz level, and can be coupled with the terahertz-level laser signal output by the laser 2. The frequency difference between the two is at the GHz level, and can be further photoelectrically converted to output a broadband frequency-doubled electrical signal. In this way, the microwave signal that is rapidly and continuously swept can achieve broadband frequency doubling.

[0056] Figure 2 The modulation principle diagram of the intensity modulator according to the embodiment of the present invention is schematically shown.

[0057] According to an embodiment of the present invention, for example, the effective length of the optical fiber connecting the second optical coupler 5 and the intensity modulator 1 and the effective length of the cable connecting the electrical coupler 11 and the intensity modulator 1 can be equal. When the effective length of the optical fiber is equal to that of the cable, it can be considered that the transmission time of the swept frequency optical signal transmitted from the second optical coupler 5 to the intensity modulator 1 and the swept frequency microwave signal transmitted from the electrical coupler 11 to the intensity modulator 1 are equal, and the optical signal and the microwave signal are of the same source. At this time, Figure 2 As shown, the frequency 2-1 of the optical signal modulated and output by the intensity modulator 1 is the superposition of the frequencies of the swept-frequency optical signal and the swept-frequency microwave signal. For example, there are mainly three cases. In the first case, the maximum value of the frequency of the optical signal modulated and output by the intensity modulator 1 is the sum of the frequencies of the swept-frequency optical signal and the swept-frequency microwave signal, realizing the broadband frequency doubling of the microwave signal. In the second case, the frequency 2-2 of the optical signal modulated and output by the intensity modulator 1 is the same as the frequency of the swept-frequency light source 4. In the third case, the frequency 2-3 of the optical signal modulated and output by the intensity modulator 1 is a single frequency, and the chirp rates of the swept-frequency optical signal and the swept-frequency microwave signal cancel each other out.

[0058] According to an embodiment of the present invention, the optoelectronic oscillator loop B may include at least one loop. For example, the number of loops may be increased by increasing the number of long optical fibers 7 connected in parallel in the optoelectronic oscillator loop B. The lengths of at least two long optical fibers 7 may be different, and thus the delay of the optical signal passing therethrough may be controlled by adjusting the lengths of different long optical fibers 7, thereby improving the single-mode characteristics of the optical signal. The long optical fiber 7 is a low-loss energy storage element that can improve the noise performance of the optoelectronic oscillator. The optoelectronic oscillator loop B is used to generate optoelectronic oscillations and maintain the state of loop oscillation.

[0059] Figure 3 The working principle diagram of the notch filter according to the embodiment of the present invention is schematically shown.

[0060] According to an embodiment of the present invention, Figure 3 As shown, 3-1a, 3-1b, 3-2a, 3-2b, 3-3a, 3-3b, 3-4a, 3-4b represent positive and negative first-order optical sidebands of equal magnitude and opposite phase, 3-5 represents a swept-frequency light source 4 in a single-frequency state, 3-6 represents a reflection spectrum of a notch filter 8, 3-7 represents a passband of a microwave photon filter (which can be regarded as an equivalent device of a swept-frequency light source 4, a phase modulator 6, a notch filter 8 and a first photodetector 9), and f MPF The frequency that the microwave photon filter can pass is equal to the difference between the frequency of the optical sideband filtered out by the notch filter 8 and the optical carrier frequency and f notch Indicates the notch frequency of the notch filter 8. During the operation of the optoelectronic oscillation loop B, when each optical sideband passes through the notch filter 8, the power of one of the equal and opposite optical sidebands (such as 3-3a) corresponding to the frequency of the notch filter 8 is offset and filtered out, and the equal and opposite optical sideband (such as 3-3b) is not offset during the beat process, so that a single optical sideband can be generated. The notch filter 8 includes, for example, any one of a phase-shifted fiber Bragg grating, a Fabry-Perot resonant cavity, a gas absorption cell or a microring.

[0061] Preferably, the notch filter 8 may be, for example, a phase-shifted fiber Bragg grating. The line width of the phase-shifted fiber Bragg grating is relatively narrow, for example, less than 100 MHz, and a higher quality signal can be obtained.

[0062] Figure 4 A diagram schematically shows a microwave generating device according to another embodiment of the present invention.

[0063] According to an embodiment of the present invention, Figure 4 As shown, the optical path of the optoelectronic oscillation loop B also includes at least one polarization controller 12, and the polarization controller 12 is used to adjust the polarization direction of the optical signal. The optical fiber used in the optical path of the optoelectronic oscillation loop B can be, for example, a polarization-maintaining optical fiber or a non-polarization-maintaining optical fiber. For cost considerations, when a non-polarization-maintaining optical fiber is used, at least one polarization controller 12 can be added to the optical path to adjust the polarization direction of the optical signal and improve the signal transmission quality.

[0064] Figure 5 A diagram schematically shows a microwave generating device according to yet another embodiment of the present invention.

[0065] According to an embodiment of the present invention, Figure 5As shown, the optoelectronic oscillation loop B includes, for example, at least one amplifier 10 that can be used to increase the loop gain and promote oscillation. The amplifier 10 can be, for example, a first optical amplifier 101 and an electrical amplifier 102, which can respectively enhance the power of the optical signal and the electrical signal in the optoelectronic oscillation loop to achieve stable oscillation of the signal in the optoelectronic loop. The frequency doubling module A also includes, for example: a second optical amplifier 13, an optical filter 14, and a second photodetector 15. Among them, the second optical amplifier 13 is used to amplify the frequency doubling optical signal. The optical filter 14 is used to filter out the non-frequency doubling optical signal output by the intensity modulator 1. The second photodetector 15 is used to convert the broadband frequency doubling optical signal into a broadband frequency doubling electrical signal.

[0066] According to an embodiment of the present invention, the microwave generating device of the embodiment of the present invention can, for example, generate a broadband frequency-doubled linear chirped microwave waveform based on Fourier domain mode locking. Among them, the swept light source 4, the second optical coupler 5, the phase modulator 6, the long optical fiber 7, the notch filter 8, the first optical amplifier 101, and the first photodetector 9 are connected in sequence, for example, by optical fiber jumpers. The second optical coupler 5, the intensity modulator 1, the second optical amplifier 13, the optical filter 14, and the first optical coupler 3 are connected in sequence, for example, by optical fiber jumpers. The laser 2, the first optical coupler 3, and the second photodetector 15 are connected in sequence, for example, by optical fiber jumpers. The first photodetector 9, the electric amplifier 102, the electric coupler 11, and the phase modulator 6 are connected in sequence, for example, by cables. The electric coupler 11 and the intensity modulator 1 are connected, for example, by cables. The swept frequency light source 4, the second optical coupler 5, the phase modulator 6, the long optical fiber 7, the notch filter 8, the first optical amplifier 101, the first photodetector 9, the electric amplifier 102, and the electric coupler 11 constitute a Fourier domain mode-locked photoelectric oscillation loop, which can generate a fast swept frequency microwave signal. The intensity modulator 1, the second optical amplifier 13, the optical filter 14, the laser 2, the first optical coupler 3, and the second photodetector 15 can realize the microwave signal frequency doubling and bandwidth doubling process.

[0067] According to an embodiment of the present invention, a frequency-swept microwave signal can be generated by an optoelectronic oscillation loop. The frequency-swept light source 4 generates a frequency-swept optical signal, and the transmission time of the frequency-swept optical signal generated by the frequency-swept light source 4 to the intensity modulator 1 is controlled to be the same as the transmission time of the frequency-swept microwave signal emitted by the electric coupler 11 to the intensity modulator 1. The frequency-swept microwave signal generated by the optoelectronic oscillation loop is modulated to the frequency-swept optical signal generated by the frequency-swept light source 4 by the intensity modulator 1, and the frequency-swept optical signal is superimposed on the frequency-swept microwave signal to achieve frequency doubling.

[0068] Specifically, the swept-frequency optical signal generated by the swept-frequency light source 4 generates positive and negative first-order optical sidebands of equal magnitude and antiphase after passing through the second optical coupler 5 and the phase modulator 6. After passing through the long optical fiber 7 and the notch filter 8, the positive and negative first-order sidebands are unbalanced. After the optical power is increased by the first optical amplifier 101, it is converted into a swept-frequency microwave signal by the first photodetector 9. After the power is amplified by the electrical amplifier 102, it is connected to the phase modulator 6 via the electrical coupler 11 to form a closed loop, constituting a Fourier domain mode-locked optoelectronic oscillation loop for generating a fast swept-frequency microwave signal. The second optical coupler 5 outputs another light input to the intensity modulator 1, and the frequency sweeping microwave signal output by the electric coupler 11 is input to the intensity modulator 1. The transmission time of the two signals is controlled to be the same. The optical signal output by the intensity modulator 1 can double the bandwidth. After being amplified by the second optical amplifier 13, it is filtered by the optical filter 14 to retain only the required frequency-doubled broadband optical signal. The laser 2 outputs a single-frequency optical signal of a suitable wavelength, which is coupled together by the first optical coupler 3 and input into the second photodetector 15 to realize the conversion of the optical signal to the electrical signal, and finally outputs a broadband frequency-doubled swept electrical signal. By adjusting the optical signal frequency of the laser 2 and the frequency sweeping light source 4, the center frequency of the frequency sweeping microwave signal can be adjusted. According to the experimental results of the microwave generating device of this embodiment, the scanning range of the broadband frequency-doubled swept electrical signal can reach 1-39GHz, and a large bandwidth of 10GHz can be achieved.

[0069] In summary, an embodiment of the present invention proposes a microwave generating device. A Fourier domain mode-locked optoelectronic oscillation loop is formed by a swept frequency light source, a phase modulator, a long optical fiber, a notch filter, a first photodetector, an amplifier and an electrical coupler, which can generate a fast swept frequency microwave signal, and the intensity modulator in the frequency doubling module is combined to modulate the homologous swept frequency optical signal and swept frequency microwave signal in the optoelectronic oscillation loop to generate a doubled frequency optical signal, which is then coupled with a laser signal generated by a laser, and finally photoelectric conversion is performed to achieve the generation of a fast swept frequency doubled microwave signal.

[0070] Figure 6 A flow chart of a microwave generating method according to an embodiment of the present invention is schematically shown.

[0071] Another aspect of the present invention provides a method for generating microwaves, such as Figure 6 As shown, the microwave generation method includes, for example:

[0072] S610, superimposing the swept frequency optical signal and the swept frequency microwave signal in the optoelectronic oscillation loop B through the intensity modulator 1 to generate a doubled frequency optical signal, wherein the maximum frequency of the doubled frequency optical signal is the sum of the maximum frequency of the swept frequency optical signal and the maximum frequency of the swept frequency microwave signal.

[0073] S620, generating a laser signal through laser 2.

[0074] S630, coupling the frequency-doubled optical signal and the laser signal through the first optical coupler 3 to generate a broadband frequency-doubled optical signal.

[0075] The details not included in the method embodiment section are similar to those in the device embodiment section. Please refer to the device embodiment section and will not be repeated here.

[0076] It should be understood that the specific order or hierarchy of steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process can be rearranged without departing from the scope of protection of the present disclosure. The attached method claims present the elements of the various steps in an exemplary order and are not intended to be limited to a specific order or hierarchy.

[0077] In the above detailed description, various features are grouped together in a single embodiment to simplify the disclosure. This method of disclosure should not be interpreted as reflecting an intention that the embodiments of the claimed subject matter require more features than are clearly stated in each claim. On the contrary, as reflected in the appended claims, the invention is in a state of having less than all the features of the disclosed individual embodiments. Therefore, the appended claims are hereby expressly incorporated into the detailed description, with each claim standing on its own as a separate preferred embodiment of the invention.

[0078] The specific embodiments described above further explain the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention. In addition, with respect to the term "comprising" used in the specification or claims, the word is covered in a manner similar to the term "including", just as "including" is explained as a transitional word in the claims. In addition, any term "or" used in the specification of the claims is intended to mean "non-exclusive or".

Claims

1. A microwave generating device, characterized in that: include: A frequency doubling module (A), the frequency doubling module (A) comprising an intensity modulator (1), a laser (2) and a first optical coupler (3); The intensity modulator (1) is used to superimpose a frequency-swept optical signal and a frequency-swept microwave signal in the optoelectronic oscillation loop (B) to generate a frequency-doubled optical signal, wherein the maximum frequency of the frequency-doubled optical signal is the sum of the maximum frequency of the frequency-swept optical signal and the maximum frequency of the frequency-swept microwave signal; The laser (2) is used to generate a laser signal; The first optical coupler (3) is used to couple the frequency-doubled optical signal and the laser signal to generate a broadband frequency-doubled optical signal; The photoelectric oscillation loop (B) comprises: A swept frequency light source (4), a second optical coupler (5), and a phase modulator (6), a long optical fiber (7), a notch filter (8), a first photodetector (9), an amplifier (10) and an electrical coupler (11) connected in a circular manner in sequence; Wherein, the swept frequency light source (4) is used to generate a swept frequency light signal; The second optical coupler (5) is used to output one channel of the swept frequency optical signal to the phase modulator (6), and output another channel of the swept frequency optical signal to the intensity modulator (1); The phase modulator (6) is used to modulate the swept frequency optical signal and a swept frequency microwave signal output by the electrical coupler (11) to generate optical sidebands of equal magnitude and opposite phases; The long optical fiber (7) is used to increase the delay of the swept frequency optical signal and the optical sidebands of equal magnitude and opposite phase in the optoelectronic oscillation loop (B); The notch filter (8) is used to filter the equal-magnitude and anti-phase optical sidebands to obtain a single optical sideband; The first photodetector (9) is used to convert the single optical sideband into the swept-frequency microwave signal; The amplifier (10) is used to amplify the swept-frequency microwave signal; The electric coupler (11) is used to output one of the swept-frequency microwave signals to the intensity modulator (1), and to output the other swept-frequency microwave signal to the phase modulator (6).

2. The microwave generating device according to claim 1, characterized in that: The effective length of the optical fiber connecting the second optical coupler (5) and the intensity modulator (1) is equal to the effective length of the cable connecting the electrical coupler (11) and the intensity modulator (1).

3. The microwave generating device according to claim 1, characterized in that: The photoelectric oscillation loop (B) includes at least one loop.

4. The microwave generating device according to claim 3, characterized in that: The photoelectric oscillation loop (B) comprises a long optical fiber (7) or at least two long optical fibers (7) connected in parallel, and the at least two long optical fibers (7) are of different lengths.

5. The microwave generating device according to claim 1, characterized in that: The notch filter (8) comprises any one of a phase-shifted fiber Bragg grating, a Fabry-Perot resonant cavity, a gas absorption cell or a microring.

6. The microwave generating device according to claim 1, characterized in that: The optical path of the photoelectric oscillation loop (B) comprises at least one polarization controller (12), and the polarization controller (12) is used to adjust the polarization direction of the optical signal.

7. The microwave generating device according to claim 1, characterized in that: The frequency multiplication module (A) further includes: A second optical amplifier (13), an optical filter (14), and a second photodetector (15); Wherein, the second optical amplifier (13) is used to amplify the frequency-doubled optical signal; The optical filter (14) is used to filter out the non-frequency-doubled optical signal output by the intensity modulator (1); The second photodetector (15) is used for converting the broadband frequency-doubled optical signal into a broadband frequency-doubled electrical signal.

8. A microwave generating method, characterized in that: include: A frequency-doubled optical signal is generated by superimposing a frequency-swept optical signal and a frequency-swept microwave signal in an optoelectronic oscillation loop (B) through an intensity modulator (1), wherein the maximum frequency of the frequency-doubled optical signal is the sum of the maximum frequency of the frequency-swept optical signal and the maximum frequency of the frequency-swept microwave signal; generating a laser signal by means of a laser (2); The frequency-doubled optical signal and the laser signal are coupled by a first optical coupler (3) to generate a broadband frequency-doubled optical signal; Wherein, the photoelectric oscillation loop (B) comprises: A swept frequency light source (4), a second optical coupler (5), and a phase modulator (6), a long optical fiber (7), a notch filter (8), a first photodetector (9), an amplifier (10) and an electrical coupler (11) connected in a circular manner in sequence; Wherein, the swept frequency light source (4) is used to generate a swept frequency light signal; The second optical coupler (5) is used to output one channel of the swept frequency optical signal to the phase modulator (6), and output another channel of the swept frequency optical signal to the intensity modulator (1); The phase modulator (6) is used to modulate the swept frequency optical signal and a swept frequency microwave signal output by the electrical coupler (11) to generate optical sidebands of equal magnitude and opposite phases; The long optical fiber (7) is used to increase the delay of the swept frequency optical signal and the optical sidebands of equal magnitude and opposite phase in the optoelectronic oscillation loop (B); The notch filter (8) is used to filter the equal-magnitude and anti-phase optical sidebands to obtain a single optical sideband; The first photodetector (9) is used to convert the single optical sideband into the swept-frequency microwave signal; The amplifier (10) is used to amplify the swept-frequency microwave signal; The electric coupler (11) is used to output one of the swept-frequency microwave signals to the intensity modulator (1), and to output the other swept-frequency microwave signal to the phase modulator (6).

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